diff --git a/readme.txt b/readme.txt
index d184f313a..17f9667d1 100644
--- a/readme.txt
+++ b/readme.txt
@@ -34,6 +34,8 @@ Set the following dependencies to this library in Visual Studio this way in the
 		./WickedEngine/mysql
 
 Editor: Use Blender 2.72 as the editor of this engine. Set up your scene and export it with the provided script
+
+Windows 7 support: define _WIN32_WINNT=0x0601 preprocessor on the whole project
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